How do I know whether I need muscle repair along with Tummy Tuck?

Thank you for the question and congratulations on your successful weight loss far.  Specific advice can only provide be provided to you after a complete history, physical examination, and a full communication of your concerns and goals. Some general thoughts however may be helpful to you:  as you know, the tummy tuck procedure typically involves plication of the abdominal wall muscle that have spread during pregnancy or weight gain/loss. IN MY OPINION, omitting this part of the procedure for the vast majority of patients who present for consultation will likely leave them with continued abdominal wall laxity and (again in my opinion) a less than optimal result. 
Best wishes.

Hello dear!!
Thanks for the question and provided information as well.
Unfortunately, without pictures, it is very difficult to give you a proper answer. l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

Although the best way to determine whether you have muscle separation is by being examined by a doctor, you can do a test on your own as well. Simply place the tips of your fingers in the mid-line of your abdomen while you’re doing a crunch. If you can fit 2 or more fingers in the space between your left and right abdominal muscles, then you may have muscle separation and a tummy tuck can correct this. If your board certified plastic surgeon examines you and finds that you don’t have muscle separation, then you don’t need to get it corrected during your tummy tuck.